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    <title>Document</title>
    <style>
        /* background-color:blue 给div标签加上一个背景色  
        标签里面需要有内容，或者有宽高 */
        div{
            background-color: blue;
            width: 200px;
            height: 200px;
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        span{
            background-color: red; 
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    <div>
        1222
    </div>
    <span>
        qwe
    </span>
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